Please help! Removed radiator valve and can't get it back on!

RainbowLaura

My radiator was stone cold, and after a quick Google I decided I needed to remove the thermostatic valve. As soon as I did, the radiator warmed up nicely and I was feeling very pleased with myself... Until I went to put it back on! It was simple to screw it off but it will not go back on. Off I went back to Google, where it seems that I should have drained the system or at very least, the radiator, before doing this! Can anyone help please? Why is nothing ever simple??

RainbowLaura

The valve in question 

Ebe_Scrooge

No need to drain anything if you're just removing the head.  Make sure the head is lined up squarely to the valve, so that the threads don't get crossed.  Often it pays to position the head on top of the valve and "unscrew" it, as it were, half a turn or so, to get the threads seated nicely.  Then you should be able to screw it back on.  It may help a bit if you open the TRV fully (to number 6) before you start, so that you're not trying to press the pin down as well when you re-fit it.

Before you do that, check that both threads are nice and clean - a quick brush with an old toothbrush should do the trick.  And a tiny smear of Vaseline on the threads may help to lubricate them if they're a bit stiff.

Oh, and while you're there, check that the pin moves up and down freely.  Press it down with the blade of a screwdriver (or even a teaspoon or something), make sure it pops back up when you release it.

Mutton_Geoff

As Scrooge says, plus you may need to rotate the base/body of the thermostat (in your hand) to align the plastic locator lugs on the sides before pressing down gently so you can then tighten up the screwed collar. There will be some resistance felt as you push that pin in a little as it will have popped out a little further than the max setting on the thermostat.

RainbowLaura

Ebe_Scrooge said:

No need to drain anything if you're just removing the head.  Make sure the head is lined up squarely to the valve, so that the threads don't get crossed.  Often it pays to position the head on top of the valve and "unscrew" it, as it were, half a turn or so, to get the threads seated nicely.  Then you should be able to screw it back on.

Before you do that, check that both threads are nice and clean - a quick brush with an old toothbrush should do the trick.  And a tiny smear of Vaseline on the threads may help to lubricate them if they're a bit stiff.

Oh, and while you're there, check that the pin moves up and down freely.  Press it down with the blade of a screwdriver (or even a teaspoon or something), make sure it pops back up when you release it.

Thank you so much, that's a relief!

Sorry to be so dense, but I'm not sure what you mean by threads? 

The pin won't budge at all, I suspect that's why the radiator hasn't been working. Would it be ok to just leave the head off completely, as it's working without it on?

RainbowLaura

underside of the head 

Ebe_Scrooge

RainbowLaura said:

Ebe_Scrooge said:

No need to drain anything if you're just removing the head.  Make sure the head is lined up squarely to the valve, so that the threads don't get crossed.  Often it pays to position the head on top of the valve and "unscrew" it, as it were, half a turn or so, to get the threads seated nicely.  Then you should be able to screw it back on.

Before you do that, check that both threads are nice and clean - a quick brush with an old toothbrush should do the trick.  And a tiny smear of Vaseline on the threads may help to lubricate them if they're a bit stiff.

Oh, and while you're there, check that the pin moves up and down freely.  Press it down with the blade of a screwdriver (or even a teaspoon or something), make sure it pops back up when you release it.

Sorry to be so dense, but I'm not sure what you mean by threads?

The screwy-together bits - top of the silver valve in your picture, and a corresponding thread in the head, where it screws on.

RainbowLaura said:

Ebe_Scrooge said:

No need to drain anything if you're just removing the head.  Make sure the head is lined up squarely to the valve, so that the threads don't get crossed.  Often it pays to position the head on top of the valve and "unscrew" it, as it were, half a turn or so, to get the threads seated nicely.  Then you should be able to screw it back on.

Before you do that, check that both threads are nice and clean - a quick brush with an old toothbrush should do the trick.  And a tiny smear of Vaseline on the threads may help to lubricate them if they're a bit stiff.

Oh, and while you're there, check that the pin moves up and down freely.  Press it down with the blade of a screwdriver (or even a teaspoon or something), make sure it pops back up when you release it.

The pin won't budge at all, I suspect that's why the radiator hasn't been working. Would it be ok to just leave the head off completely, as it's working without it on?

It needs to budge.  Give it a spray of WD40 or a drop of oil, press it down firmly.  Might need to be quite firm with it, but it'll go.  Since you say the radiator is warm, that would suggest the pin is stuck in the "up" position now, but was previously stuck in the "down" (cold) position.  Give it a bit of lubrication and a bit of persuasion, it should free up.  A stuck pin is very common on TRVs, but should be simple to free it up.

It won't do any harm to leave it off, but it means you won't be able to control the temperature of that radiator.

Mutton_Geoff

The pin is usually very stiff, it's a water valve. You won't be able to push it with your finger, use a flat metal object, coin etc on top and push hard, you'll feel it move down. The chrome ring on the bit in your hand turns freely. Place the stat over the top of the valve again, push down and as you do turn the chrome ring onto the threaded part of the valve and push down, turn right (viewed from above, righty tighty, lefty loosey) until it's as tight as you can get.

It will work fine left off but not moneysaving at all as the rad won't go off when the room is warm enough.

If it's stiff/stuck, you can use a drop of olive oil on that pin as you push it up and down to free it. It's common for them to get stuck in one position.

Nearlyold

If you'd removed the valve without draining down you'd already have water everywhere!! Thankfully you have sensibly only removed the Thermostatic Head (that's the bit in your right hand that has the number 5 on it).

The thermostatic head controls the flow of hot water through the radiator by pressing down on the brass pin you can see poking out of the circle of black plastic on the chrome valve body in the left of the picture, the pin is sprung loaded you can press it down with a suitable hard object to get an idea of how stiff it is and to loosen it a bit. Don't hit it though! 

When putting the Thermostatic Head back on the valve, make sure it's set on the maximum temperature (looks like you have partially already done that as its set to 5, though it appears you can turn it some more to 6 or maybe higher), then when putting it back on the chrome valve body you have to press it down firmly (to overcome the spring tension pushing the brass pin up) you should then be able to engage the internal threads on the grooved chrome ring (that's the ring at the bottom of the thermostatic head) with the threads on the top of the chrome valve body. Might take a few attempts to get it to all line up - just make sure you don't get it cross threaded

diystarter7

Hi OP

Put the head that you have in your hand squarely on top of where it was removed from.
Then slowly turn the chrome bit at the bottom ie the top you have in your hand

Mary the two like you are gently trying to get a nut on a bolt -

just do the revesrse but it is about lining it up properly

Have the numbers on the head facing outwards where you can see them and tunr the silver spindle

job done

Btw, ensure the head is at the open setting so the bit inside is up and makes it easier to refit.

diystarter7

Hi

Very easy video to follow - watch it from 39 seconds into video.
Very clear and easy to follow

https://www.youtube.com/watch?v=qkN700ijZ5Q

Thanks